Mount speed doesn't override speed of the mob on it

RiderBoss:
  Type: STRAY
  Skills:
  - skill {s=MagicShot2} ~onDamaged 0.3 =80%-100%
  - skill {s=ScoutSummon} ~onDamaged 0.3 =80%-100%
  Display: '&b&lRider'
  Health: 500
  Damage: 12
  Equipment:
  - RiderSword:0
  - RiderHelmet:4
  BossBar:
    Enabled: true
    Title: 'Rider'
    Range: 100
    Color: PURPLE
    Style: SEGMENTED_10
    CreateFog: true
    DarkenSky: true
    PlayMusic: false
  Mount: RiderMount...